 We read with interest the National Association of EMS Physicians (NAEMSP) position paper "Patient Restraint in Emergency Medical Services Systems" by Kupas and Wydro recently published in Prehospital Emergency Care.(1) Although we are in strong support of discussion and research on the important topic of patient restraint in the prehospital setting, the position statement raises a number of issues that require critical evaluation and deserve further commentary.

Kupas and Wydro state that "patients should never be transported while hobbled, 'hog-tied,' or restrained in a prone position (which) has been associated with asphyxia." As evidence, Kupas and Wydro reference two articles. The first by Stratton et al.(2) is a report of two cases of sudden death in patients who were restrained by prehospital providers. As a limited case series, this report offers no firm evidence that the prone restraint position causes or increases the risk for asphyxiation. The second reference by Roeggla et al.,(3) in which volunteer subjects were placed in a variety of restraint positions with physiologic monitoring, is flawed in that the authors make conclusions about ventilatory changes in the restraint position that are not validated by the data they present. Their study demonstrated no hypoxia or hypercarbia with the restraint position to suggest an increased risk of asphyxiation.

The theory of positional asphyxia as it relates to restraint has largely been based on the work of Reay et al,(4) in 1988 in which volunteer subjects were placed in the sitting and restraint positions after exercise with pulse oximetry and heart rate monitoring. Since his original work, in which the positional asphyxia term gained notoriety, Reay(5) has retracted his conclusions about the physiologic effects of the hobble position based on "more comprehensive" clinical research. This new research included a study by Chan et al.(6) in which subjects were placed in the sitting, supine, prone, and hobbled positions with spirometric, arterial blood gas, pulse oximetry, and cardiovascular monitoring, in which no significant change to suggest increased risk for asphyxiation was demonstrated. These findings have further been confirmed by other similar studies.(7,8) Reay himself has written that the hobble position is "physiologically neutral" and that other factors must be considered in these cases of sudden death.(9)

Our concern is that the NAEMSP position paper might give emergency medical services (EMS) providers the false impression that avoiding the hobble or hog-tie position provides a measure of safety when dealing with patients who require restraint in the field. Prehospital Emergency Care itself has reported on sudden deaths that have occurred in individuals who were restrained in the sitting and supine positions, as well as the prone or hobbled position.(10) This case report would seem to provide as much "evidence" as the Stratton case report, but was not considered by Kupas and Wydro. These deaths are likely secondary to the drug-induced or psychiatric-associated excited delirium that led to the restraint in the first place, rather than the position itself. The fact that there are reports of sudden death in patients restrained in the supine and sitting positions as well as prone and hobble positions supports this contention.(10) Again, by recommending restraining a patient supine, sitting, or a side position, a false sense of safety is given to the EMS providers that does not exist.

We commend the authors for emphasizing the need to never leave a restrained patient unattended and to perform and document frequent neurovascular assessments of the extremities that are restrained. Given the numbers of cases of sudden death that occur to restrained individuals in all positions, we would recommend rhythm monitoring, when possible, in all restrained patients with frequent cardiopulmonary assessments as well.

We support the need for a position statement on this topic, but do not want EMS providers to think that just because an agitated patient is not in a hobble or prone restraint position, the risk of sudden death is any less. All agitated, restrained patients are at risk for sudden death, and thus vigilance of cardiopulmonary status is paramount.

 We thank Drs. Vilke, Chan, and Neuman for their interest in the NAEMSP position paper on patient restraint.(1) We appreciate their thoughtful comments related to restraining patients in the prone or hobble positions.

Vilke and colleagues express a concern that there is not firm evidence associating deaths in restrained individuals to the prone or hobble positions. We appreciate their discussion and evaluation of the literature on this topic. In the position paper, we discuss this topic in a single paragraph. We introduced the topic by stating that these positions have "been the suggested cause of several deaths during both police and EMS transport." We conclude the paragraph by affirming that "a similar study by Chan et al.(2) had less dramatic results" than other cited evidence, and we state that their study showed "no evidence of hypoxia or hypercapnea." Vilke et al. make a strong argument that these restraint positions by themselves have not been proven to cause death, and we agree with this point. Despite their comments, Vilke et al. do not make any statement that advocates for the general use of these positions during restraint of violent patients.

We should note that none of the physiologic studies related to the prone or hobble positions were performed on individuals who were violently struggling against the restraints or were under the influence of adrenergic or sedating drugs. We do not know what effect other medical conditions, psychiatric conditions, violent agitation, or drug intoxication would have on the physiologic effects of prone or hobble restraint positions. Additionally, although deaths have been reported in the prone, hobble, sitting, and supine positions of restraint, without knowing the actual incidence of these occurrences, it is impossible to make any conclusions about the safety or danger of any of these positions based on these reports.

Vilke and colleagues state that their "concern is that the NAEMSP position paper may give EMS providers the false impression that avoiding the hobble or hog-tie position provides a measure of safety when dealing with patients who require restraint in the field." We do not believe that this is a conclusion to be drawn from the position paper. The paper lists 17 recommendations related to prehospital patient restraint, and the recommendation to avoid prone or hobble restraint is only a part of one of these 17 recommendations. Clearly, we believe that there are many issues related to prehospital patient restraint, and no single recommendation in the position paper will provide complete safety for the patient.

Vilke and colleagues also suggest that "Given the numbers of cases of sudden death that occur to restrained individuals in all positions, we would recommend rhythm monitoring, when possible, in all restrained patients with frequent cardiopulmonary assessments as well." This statement is further reason to avoid prone or hobble restraint positions, because cardiopulmonary assessments are more easily accomplished when the patient is in the supine position.

We agree with frequent cardiopulmonary assessments as stated in one of the position paper recommendations. "After patient restraint, there must be regular and frequent evaluation of the neurovascular status of all restrained extremities and the respiratory and hemodynamic condition of the patient."(1) Although electrocardiographic rhythm monitoring may be indicated in some restrained patients, it is not necessary for every restrained patient as suggested by Vilke et al. Patients with medical indications for monitoring probably require rhythm monitoring when available. Examples of these include patients with drug overdoses or altered levels of consciousness. There is a wide spectrum of patients who require restraint, and basic life support ambulance personnel can appropriately manage many of these. Suggesting that all restrained patients receive rhythm monitoring may be very restrictive to EMS systems with limited advanced life support resources.

We still believe that patients should never be transported while hobbled, "hog-tied," or restrained in a prone position with hands and feet behind the back. We thank Drs. Vilke, Chan, and Neuman for their excellent and thoughtful discussion of the physiology of prone and hobble restraint.